/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package org.apache.geode.internal.offheap;

import java.nio.ByteBuffer;
import java.util.Arrays;

import org.apache.geode.cache.Region;
import org.apache.geode.internal.cache.BytesAndBitsForCompactor;
import org.apache.geode.internal.cache.EntryBits;
import org.apache.geode.internal.cache.EntryEventImpl;
import org.apache.geode.internal.cache.RegionEntry;
import org.apache.geode.internal.cache.RegionEntryContext;

/**
 * Used to represent stored objects that can be stored
 * in the address field.
 * The RegionEntry for an off-heap region uses a primitive
 * long to store the off-heap address of the entry's value.
 * If the value can be encoded as a long (i.e. its serialized
 * representation will fit in the 8 bytes of a long without looking
 * like an actual off-heap address) then these tiny values on an
 * off-heap regions are actually stored on the heap in the primitive
 * long field. When these values are "objectified" they will be an
 * instance of this class.
 * Instances of this class have a very short lifetime.
 */
public class TinyStoredObject extends AbstractStoredObject {
  private final long address;
  
  public TinyStoredObject(long addr) {
    this.address = addr;
  }
  
  @Override
  public long getAddress() {
    return this.address;
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) {
      return true;
    }
    if (o instanceof TinyStoredObject) {
      return getAddress() == ((TinyStoredObject) o).getAddress();
    }
    return false;
  }
  
  @Override
  public int hashCode() {
    long value = getAddress();
    return (int)(value ^ (value >>> 32));
  }

  @Override
  public int getSizeInBytes() {
    return 0;
  }

  public byte[] getDecompressedBytes(RegionEntryContext r) {
    if (isCompressed()) {
        byte[] bytes = OffHeapRegionEntryHelper.decodeAddressToRawBytes(getAddress());
        long time = r.getCachePerfStats().startDecompression();
        bytes = r.getCompressor().decompress(bytes);
        r.getCachePerfStats().endDecompression(time);
        return bytes;
    }
    return getRawBytes();
  }

  /**
   * If we contain a byte[] return it.
   * Otherwise return the serialize bytes in us in a byte array.
   */
  public byte[] getRawBytes() {
    return OffHeapRegionEntryHelper.decodeUncompressedAddressToBytes(getAddress());
  }
  
  @Override
  public byte[] getSerializedValue() {
    byte[] value = getRawBytes();
    if (!isSerialized()) {
      value = EntryEventImpl.serialize(value);
    }
    return value;
  }

  @Override
  public Object getDeserializedValue(Region r, RegionEntry re) {
    return OffHeapRegionEntryHelper.decodeAddressToObject(this.address);
  }

  @Override
  public void fillSerializedValue(BytesAndBitsForCompactor wrapper,
      byte userBits) {
    byte[] value;
    if (isSerialized()) {
      value = getSerializedValue();
      userBits = EntryBits.setSerialized(userBits, true);
    } else {
      value = (byte[]) getDeserializedForReading();
    }
    wrapper.setData(value, userBits, value.length, true);
  }

  @Override
  public int getValueSizeInBytes() {
    return 0;
  }
  
  @Override
  public boolean isSerialized() {
    return OffHeapRegionEntryHelper.isSerialized(this.address);
  }

  @Override
  public boolean isCompressed() {
    return OffHeapRegionEntryHelper.isCompressed(this.address);
  }

  @Override
  public void release() {
    // nothing needed
  }

  @Override
  public boolean retain() {
    return true;
  }

  @Override
  public int getRefCount() {
    return -1;
  }

  @Override
  public int getSize() {
    return Long.BYTES;
  }

  @Override
  public int getDataSize() {
    return OffHeapRegionEntryHelper.decodeAddressToDataSize(this.address);
  }

  @Override
  public byte readDataByte(int offset) {
    return getRawBytes()[offset];
  }

  @Override
  public void writeDataByte(int offset, byte value) {
    throw new UnsupportedOperationException("ObjectStoredAsAddress does not support modifying the data bytes");
  }

  @Override
  public void readDataBytes(int offset, byte[] bytes) {
    readDataBytes(offset, bytes, 0, bytes.length);
  }

  @Override
  public void writeDataBytes(int offset, byte[] bytes) {
    writeDataBytes(offset, bytes, 0, bytes.length);
  }

  @Override
  public void readDataBytes(int offset, byte[] bytes, int bytesOffset, int size) {
    byte[] src = getRawBytes();
    int dstIdx = bytesOffset;
    for (int i = offset; i < offset+size; i++) {
      bytes[dstIdx++] = src[i];
    }
  }

  @Override
  public void writeDataBytes(int offset, byte[] bytes, int bytesOffset, int size) {
    throw new UnsupportedOperationException("ObjectStoredAsAddress does not support modifying the data bytes");
  }

  @Override
  public ByteBuffer createDirectByteBuffer() {
    return null;
  }

  @Override
  public boolean hasRefCount() {
    return false;
  }

  @Override
  public boolean checkDataEquals(StoredObject so) {
    return equals(so);
  }

  @Override
  public boolean checkDataEquals(byte[] serializedObj) {
    byte[] myBytes = getSerializedValue();
    return Arrays.equals(myBytes, serializedObj);
  }

  @Override
  public long getAddressForReadingData(int offset, int size) {
    throw new UnsupportedOperationException("ObjectStoredAsAddress does not support reading at an address");
  }

  @Override
  public StoredObject slice(int offset, int limit) {
    throw new UnsupportedOperationException("ObjectStoredAsAddress does not support slice");
  }
}